<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>

<script>
  var a = [{name: '200',content: ['ahaha']},{name: '300',content: ['ahaha']},{name: '400',content: ['ahaha']}];
  var b = [{name: '200',content: ['bhaha']},{name: '300',content: ['bhaha']},{name: '600',content: ['bhaha']},{name: '700',content: ['bhaha']}];
  var c = b.concat(a);
  
  a.map((item1,ind1) => {
    b.map((item2,ind2) => {
      if(item2.name == item1.name){
        item1.content = item2.content.concat(item1.content);
        b.splice(ind2,1);
      }else{
        
      }
    });
  });
  console.log(b.concat(a));
</script>
</body>
</html>